Dart type plug



Feb. 7,1939. G 5 O 2,146,219

DART TYPE PLUG I Filed June 9, 1937 4 Sheets-Sheet 1 I a: i

as r Inventor. 27 Granville ,5; I 07 G. S. KNOX DART TYPE PLUG Feb. ,1939.

4 Sheets-Sheet 5 Filed June 9, 1957 2 V 8 wiii i In venlon (Franz/111165. Knox.

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G. s. KNOX DART TYPE PLUG Feb. 7, 1939.

Filed June 9, 1937 4 Sheets-Sheet 4 In venion Granville J. Kn oac.

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Patented Feb. 7, 1939 UNITED STATES DART TYPE PLUG Granville S. Knox, Los Angeles, Calif., assignor to Hydril Company, Los Angeles, Calif., a corpora.-

tion of California Application June 9, 1937, Serial No.- 14'7,266

14 Claims.

This invention pertains generally to plugs adapted to be lowered and set within well pipe to close the pipeagainst the upward flow of fluid therethrough. More specifically, the invention is an improvement upon the form of plug disclosed in a copending application of Frederick Stone and Granville S. Knox, entitled Well pipe plug, Ser. No. 81,466, filedMay 23, 1936. The present type of plug is particularly adapted for use as a means for closing and facilitating the removal of drill pipe after the occurrence of a twist-oil, and the invention will be described, typically, with that main objective in view.

Occasionally during well drilling operations, the drill string, comprising successive lengths of pipe connected by couplings, becomes severed above the usual back pressure valve as a result of torsional or other strains, so that it is necessary to remove the upper severed section from the well and to then recover the lower section. In case the well is flowing gas or liquid, the upper severed section of the drill string is customarily pulled through a packinghead on the casingthat holds the well pressure and prevents fluid leakage around the drill pipe. When the twist-off occurs above the standard back pressure valve, the upper severed section of the pipe remains open, unless plugged, to release the well fluid. One of the major objects of the invention is to keep the upper or twisted-01f section of the drill pipe closed. against the escape of well fluid therethrough as the pipe is being pulled, by the use of an improved type of plug which is pumped or otherwise moved down within the pipe and finally positioned to close the pipe at or near its lower severed end. In its preferred form, the plug comprises expansible packer and pipe engaging means, both of which are maintained in radially contracted condition as the plug is being pumped downwardly through the pipe, and which are releasable to seal off around the plug and to hold it against subsequent longitudinal movement in the pipe. One of the principal features of the invention is the provision of a control device whereby the packer and pipe engaging means are automatically caused to expand by virtue of movement of a portion of the plug out of the lower open end of the pipe.

The principal features of novelty and 'main objects of the invention can perhaps most clearly be explained briefly by comparing the present plug with the invention disclosed in the copending application referred to abov Although that invention is not in its broader aspects limited to a plug requiring cooperation with any particular 55 type of jointed pipe, the specific form of plug shown in the copending application is particularly designed for cooperation with an external flush joint drill pipe having internal shoulders which determine the set position of the plug by reason of the engagement between pipe engaging means carried by the plug, and the pipe couplings. In that case, the plug has certain dimensional characteristics, relative to the pipe stand lengths, that insure final positioning of the plug at predetermined locations relative to the lower end of the drill pipe.

The principal object of the present invention is to provide a plug of this same general type, (i. e., one having pipe engaging means, and also, preferably, a packer, thatare radially expanded by movement of a lower portion of the plug out of the lower end of the drill pipe) in which the pipe engaging means is capable of setting the plug at any longitudinal point in the drill string, as distinguished fromthe previous form in which the set position of the plug is determined by the location of the pipe couplings. In accordance with the invention, I provide a form of gripping means, typically and preferably wedge slips, which when actuated in the manner explained, are capable of engagement with the smooth cylindric bore of the pipe to hold the plug against vertical movement therein. A further feature of the invention is the provision of this type of pipe engaging means, operable upon release or actuation to arrest continued downward movement of the plug within the pipe. In addition, I.preferably provide pipe gripping means for preventing upward movement of the plug from set position, so that at the point of operation, the plug is held against both-upward and downward movement.

The invention embodies numerous additional features and objects, as well as improvements in details of construction, but all these can best be explained without necessity for further preliminary discussion, by referenceto the accompanying drawings showing the invention in certain of its typical and illustrative forms. Throughout the description to follow, the drawings, in which:

Fig. 1 is a general'view, partly in section, showing the plug positioned above the Kelly cock and before being released to be dropped or pumped down through the drill string;

Fig. 2 is a view similar to plug released for strin Figs. 3, 4 and 5 are longitudinal sectional views, continuing in downward progression in the order named, showing the plug parts in set position Fig. 1 showing the passage down through the drill reference is made to with the latch arms confined within the drill Figs. 6, 7 and 8 are sectional views similar respectively to Figs. 3, 4 and 5, showing the plug parts in released positions with the packer readily expanded and the pipe gripping means projected radially into engagement with the pipe;

Figs. 9, 10 and 11 are enlarged cross sectional views taken on lines 99, ||l-| and respectively, in Figs. 4 and and Fig. 12 is a fragmentary sectional view showing a variational form of the invention.

Referring to the drawings, the plug generally indicated at 20 has a normal diameter sufliciently small to enable the plug to pass freely down through the drill string 2|. As previously mentioned, the plug being particularlyadapted for use in drilling strings made up of internal flush type joints, is provided with gripping means capable of engaging the smooth cylindric wall of the pipe to hold the plug against vertical movement therein. The plug 20 may be generally described as comprising a tubular body 23 of suliicient length that after passage of the later described latch out of the lower end of the pipe, the expansible packer and pipe engaging means will be set within the pipe at points located above its lower end. The body 23 carries pipe engaging means, generally indicated at 24 and 25, adapted to hold the plug against upward and downward movements, respectively, within the pipe, and an expansible packer 26 normally maintained in radially constricted condition, but releasable for expansion into fluid tight engagement with the pipe. It will suflice to note at this point that both the packer 26 and the pipe engaging means 25, are maintained in radially contracted positions during downward passage of the plug to setting position, arid that both are expanded by virtue of the movement of the latch device, generally indicated at 21, out of the lower open end 2 la of the drill string.

The body 23 comprises a pair of tubular sections 28 and 29 connected by coupling 36, and an enlarged diameter section 3| connected at 32 to the upper end of section 28. Screw-threaded on the lower end of body section 29 is a latch body 33, the purpose and particular construction of which will later be explained more in detail. It will be understood that the tubular body of the plug may be made up and assembled in any suitable manner, and that the specific form illustrated is to be regarded as typical only.

The packer assembly 26 comprises an elongated rubber sleeve 34 placed about a mandrel 35 movable vertically with relation to the body and slidably extending through the bore 36 of a. fitting 31 threaded into the upper end of the enlarged diameter body section 3|. The upper end 34a of the packer preferably is internally reenforced with fabric or other suitable material, and is held to the mandrel by seating within the annular undercut mandrel recess 38. That portion of the packer sleeve 34 below the mandrel recess 38 is longitudinally movable on the mandrel, and

is radially expansible into fluid tight engagement with the pipe 2| by axial compression and upward movement of the tapered portion 49 of the packer relative to the correspondingly tapered portion 50 of the mandrel. The lower end of the sleeve 34 is annularly recessed at 5| toform lips 52 and 53 that normally are confined within the upper box end 31a of fitting 31, the interior of the box being in communication with the bore of the body through passages 54. Upon upward movement of the mandrel 35 relative to the body 23, the lower end of the packer sleeve is withdrawn from box 31a, freeing the lips 52 and 53. Then, fluid pressure within the pipe below the packer acts to radially expand the latter by forcing lips 52 and 53 into fluid tight engagement with the pipe and mandrel, respectively, and axially compressing the sleeve by forcing it upward along the mandrel.

During downward passage of the plug in the drill string, the packer 34 is held confined within box 31a by an elongated rod 55, comprising sections 56 and 51 interconnected by a coupling 58 that has a slack connection with the lower end of the mandrel 35 by way of a thimble coupling 59, through the bottom of which the upper end of rod 56 extends. Rod 55 carries on its lower end a member 60 comprising a part of the latch 21, and having oppositely positioned notches 6| which receive the ends 62 of a pair of latch elements 63 contained within longitudinal slots 64 in the body 33 and pivotally mounted on pins 65. When the plug is inserted within the pipe, the parts are set in the positions shown in Figs. 3 to 5, with rod 55 held against upward movement by the latch elements 63, the latter in turn being prevented by engagement with the pipe 2| from releasing the rod.

The pipe gripping means 24 and 25 comprise sets of vertically movable wedge slips 66 and 61 (four slips typically being shown in each set) carried by a sleeve 68 mounted on body section 28, the sleeve being confined between shoulder 69 and the lower end of upper body section 3|. Sleeve 68 contains longitudinally extending ways and 1| which receive the slips 66 and 61, the base surfaces 12 and 13 of the ways being oppositely inclined so that the upper slips 66 are radially expanded by downward movement relative to the sleeve 63, and the lower slip 61 by upward movement with relation to the sleeve. As best illustrated in Fig. 9, the slips are confined in their respective ways by flanges 61a projecting laterally within longitudinal grooves at the sides of the ways.

Merely for the purpose of illustrating the range of upward and inward movement of slips 66, the latter are shown in Fig. 4 to be positioned at the uppermost ends of the ways 10. In actual operation, however, these slips will drop by gravity to positions of engagement with the pipe, permitting downward movement of the plug but preventing its upward movement by reason of the wedglng engagement between surfaces 12 and the correspondingly shaped inner surfaces 66a of the slips. Lower slips 61 are releasably held against upward movement relative to sleeve 68, by a suitable connection with the latch controlled rod 55. As a typical form of connection between the slips and rod, I show a sleeve 16 slidable longitudinally on the body and carrying a ring 11 connected to slip 61 by rods 18, the latter having suflicient flexibility to permit radial expansion of the slips. Sleeve 16, ring 11 and rod 55 are connected for vertical movement together by a pin 18 passing through a transverse hole in the rod coupling 58 and through a pair of vertically extending slots 86 within body section 28, the slots being suificiently long to permit movement of the latch rod and associated parts within their limits of travel. A coil spring 8| encircling the body and normally compressed between the ring 11 and coupling 30, operates to elevate and radially expand the slips 61 into pipe engaging positions, upon release of rod 55 by the latch device 21 at the point of its 9,148,219 movement out of the lower end or the drill pipe.

In setting the plug preparatory to its insertion within the drill string, assume the parts to be in theexpanded positions of Figs. 6, 7 and 8. By removing cap screw 8| in the lower end of the latch body 33, and threading a suitable setting tool (not shown) into socket 82 in the lower end of member 60, the latch rod 55 may be pulled downwardly until the lower end of the packer sleeve 34 contacts the end of the box member 31a. The lipped end of the rubber sleeve is then worked into the counterbore of the box, and the latch rod then pulled further downward until the latch teeth 62 mesh with notches 6| in member 50. Further downward movement of the rod swings the latch member 63 completely into slots 64 and moves the lowerend of the packer sleeve into confined position within the box 31a. The

parts may now be releasably held in their set positions by inserting a thumb screw 83, see Fig.

, 10, through ring 11 and sleeve I6 into recess 84 within the body section 28. As will appear, when the plug is inserted within the drill pipe, set screw 83 is removed. It is shown in the view of Fig. 10 merely for convenience of illustration. After removing the setting tool from the nose of the plug and replacing cap screw 8|, the plug is ready for use.

While the plug may be inserted Within the drill pipe in any suitable manner, Figs. 1 and 2 will illustrate a typical sequence of operations for introducing the plug. In Fig. 2, the drill string 2| is shown to extend upwardly through a conventionally illustrated packing head 86 on the casing 81, and to be connected by coupling as with the usual kelly 89. The drill string is supported by slips 90 within the diagrammatically illustrated table 9|, and the upper end of the kelly carries the usual cock 92 below the swivel 93 through which circulating fluid is discharged downwardly through the pipe string, when cock 92 is open, from the rotary hose 94 via goose neck 95 above the swivel. In operation, the plug 20 is inserted suflloiently far into or through the swivel 93 that the latch elements 63 will be confined to the extent that they are prevented from folding completely over to released positions and tripping the plug. Thumb screw 83 then is removed, permitting the latch elements to spring outwardly'into engagement with the pipe. The plug now may be dropped to rest on top of cook 92, the latter being in closed position. A pipe 95, closed at'its upper end by cap 91, then is lowered over the plug and 55 threaded at 98 into the upper end of the goose neck. Cock 92 next is. opened and circulating fluid is pumped through the goose neck to force the plug downwardly into and through the pipe string 2|. I

The plug is forced down through the pipe string until its lower end passes out the open end 2Ia of the pipe which, as illustrated, is the location of the twist-off. Whenthe nose of the plug passes out of the end 2Ia of the pipe, latch elements 63 are thrown outwardly and out of locking engagement with the latch rod, into the released positions shown in Fig. 8, in which the latch elements are received within the lower portions of slots 64 below the pin 65. Upon release of the latch rod to the position of Figs. 6 to 8, a coil spring I00 confined between body shoulder MI and the upper flanged end 59a of the connecting member 59, thrusts the mandrel 35 upwardly with relation to the body, withdrawing the lower end of the packer from box 31a. Upward movement of the mandrel is limited by member 59 coming into engagement with the lower end of fitting 31. When initially withdrawn from confinement, the lower lipped end of the packer, and theportion of the packer sleeve above, assume a position substantially as illustrated by the dotted lines of Fig. 6, in which the packer lip 52 expands by its resiliency into engagement with the pipe 2|. Thereafter, the upwardly applied well pressure acts to force lips 52 and 53 tightly into engagementwith the mandrel and pipe, and also to longitudinally compress that portion of the packer below mandrel recesses 38 by upward movement relative to the mandrel. As the packer is forced upwardly, it is expanded into tight engagement with the drill pipe both by the expansibility of the rubber upon compression, and by the effect of the mandrel taper to expand the rubber. It may be men tioned that spring I00 serves also as a means for checking continued downward movement of the mandrel 35, due to its inertia, to the extent of preventing the packer from becoming forced against the upper end ofbox 31a as downward progress of the plug is suddenly stopped by the action of the pipe gripping means.

Simultaneously with the setting of the packer, thewedge slips 24 and 25 are brought into gripping engagement with the pipe to hold the plug against vertical movement in either direction. As the latch rod is released, slips 6'! are thrust upwardly along wedge surfaces 13 and expanded into engagement with the pipe, by the action of spring BI. As downward, movement of the plug is thus arrested, the upper slips 66 wedge into engagement with the pipe to hold the plug against upward movement. With the plug now set within the pipe, the drill string may be pulled from the well. To remove the plug from-the pipe, the cap. screw 84 may be removed from the nose of the plug and the setting tool inserted, so that the latch ,rod may be pulled downwardly to the extent of for locking the spring actuated, slip operating sleeve against upward movement with relation to the body, until the latch rod has become released. In the variational form, the lower set of slips connected to flexible rods I03 are actuated by sleeve I04 when thrust upwardly by coil spring I05 maintained in adjustable compressed condition by nut I06 threaded on body section 20'. When rod is retained by the latch 21', sleeve I04 is locked against upward movement on the body by balls I01 contained within openings I08 in the tubular body and projecting outwardly withinv recess I09 in the upper end of the sleeve, the balls being in engagement with the inclined cam surface IIO. Upon release. and upward movement of the latch rod, balls I01 are displaced inwardly into longitudinally extending slots III in the rod coupling 58-, sufliclently far to permit sleeve I04 to travel upward in its sleeve actuating movement.

. In the foregoing description, I have referred to the plug as being operated by movement out of the lower open end of a severed pipe. It will of course be understood that the utility and operativeness of the plug are not limited to situations where a pipe happens to be severed, as at a twistofi, and that the plug may be caused to operate automatically upon movement out of the lower end of any pipe below which there is suflicient space for release of the latching mechanism. It is also to be understood that such terms as upward, downward", lowered", vertical and vertically are to be regarded as relative only; that is, these terms are employed merely for convenience of terminology in defining direction or position with reference to a vertically extending pipe or a lower open end of such pipe.

I claim:

1. A well pipe plug comprising a body, a vertically movable sleeve on said body, wedge slips mounted on the body and expansible by movement of said sleeve to prevent downward movement of the plug within the well pipe, yielding means tending to move said sleeve in a direction to expand said slips, and means releasably holding said sleeve against movement in said direction.

2. A well pipe plug comprising a body, a vertically movable sleeve on said body, wedge slips mounted on the body and expansible by movement of said sleeve to prevent downward movement of the plug within the well pipe, yielding means tending to move said sleeve in a direction to expand said'slips, means releasably holding said sleeve against movement in said direction, and wedge slips engageable with the pipe to prevent upward movement of the plug therein.

3. A plug adapted to be moved downwardly through a well pipe that is open at its lower end,

said plug comprising a radially expansible packer, a member controlling the expansibility of said packer, radially movable means for gripping the inside cylindric surface of the pipe to hold the plug against downward movement therein, yielding means operable to' actuate said packer control member to cause radial expansion of the packer, and to radially expand said gripping means into holding engagement with the pipe at a point above its lower end, and means carried by the plug and controlled by confinement within the pipe, the last mentioned means being operable by movement out of the pipe to actuate said yielding means.

4. A plug adapted to be moved downwardly through a well pipe that is open at its lower end, said plug comprising a radially expansible packer, a member controlling the expansibility of said packer, radially movable means shaped to bite into and grip the inside cylindric surface of the pipe to hold the plug against vertical movement therein, operating means for actuating said packer control member to cause radial expansion of the packer, and for radially expanding said gripping means into holding engagement with the pipe at a point above its lower end, and means positioned below said gripping means and controlled by conflnement within the pipe, the last mentioned means being operable by movement out of the lower end of the pipe to actuate said operating means.

5. A plug adapted to be moved downwardly through a well pipe that is open at its lower end, said plug comprising a radially expansible packer, a member controlling the expansibility of said packer, radially movable wedge slips adapted to grip the inside cylindric surface of the pipe to hold the plug against vertical movement therein, yielding means operable to actuate said packer control member to cause radial expansion of the packer, and to radially expand said wedge slips into holding engagement with the pipe at a point above its lower end, and means positioned below said wedge slips and controlled by confinement within the pipe, the last mentioned meansbeing operable by movement out of the lower end of the pipe to actuate said yielding means.

6. A plug adapted to be moved downwardly through a well pipe that is open at its lower end, said plug comprising a radially expansible packer, a member controlling the expansibility of said packer, radially movable means for gripping the inside cylindric surface of the pipe to hold the plug against downward movement therein, yielding means operable upon movement of a lower portion of said plug out of the lower end of the pipe to actuate said packer control member to cause radial expansion of the packer, and to radially expand said gripping means into holding engagement with the pipe at a point above its lower end, means carried by the plug below said gripping means and operable by movement out of the pipe to actuate said yielding means, and manually releasable means for holding said packer and gripping means in radially contracted condition when the plug is outside the pipe.

7. A plug adapted to be moved downwardly through a well pipe that is "open at its lower end, said plug comprising a tubular body, a plurality of radially movable members for gripping the inside cylindric surface of the pipe to hold the plug against vertical movement therein, a movable sleeve surrounding the body and attached to said gripping members, and means for radially expanding said gripping means into holding engagement with the pipe at a point above its lower end, the last mentioned means including yielding means operable to move said sleeve and to radially expand the gripping means, and means positioned below said gripping means and controlled by confinement within the pipe, the last mentioned means being operable by movement out of the lower end of the pipe to actuate said yielding means.

8. A plug adapted to be moved downwardly through a well pipe that is open at its lower end, said plug comprising a body, wedge slips mounted on the body, a slip actuating sleeve surrounding the body, means operable to move said sleeve to cause said slips to engage the pipe and hold the plug against continued downward movement within the pipe, the last mentioned means including a sleeve actuating spring expansible longitudinally of the body, and means positioned below said slips and controlled by confinement within the pipes the last mentioned means being operable by movement out of the pipe to actuate the first mentioned means.

9. In a plug adapted to be moved downwardly through a well pipe, a packer adapted to be expanded radially into fluid tight engagement with said pipe, control means comprising a member having a bore receiving one end of the packer and maintaining said packer in radially constricted condition during downward passage of the plug in said pipe, radially movable wedge slips adapted to engage the inside of said pipe to hold the plug against downward movement therein, and means carried by the plug below said slips and movable out of the lower end of the pipe, said means operating by virtue of such movement to actuate both said packer control means and pipe engaging means to expand the packer and pipe engaging means within said pipe at points spaced above its lower end.

10. In a plug adapted to be moved downwardly through a well pipe, a packer adapted to be expanded radially into fluid tight engagement with said pipe, control means comprising a member I and maintaining said packer in a radially con-- stricted condition during downward passage of the plug in said pipe, radially movable wedge slips adapted to engage the inside of said pipe to hold the plug against upward movement therein, and

means for actuating both said packer con'trol means and wedge slips to expand the packer and slips within said pipe at points spaced above its lower end, the last mentioned means comprising a member movable vertically within the plug, a spring tending to move said member to cause the packer and wedge slips to expand within said pipe, and a latch for releasably holding said member against movement by the spring, said latch operating to release said member by movement of the latch out of the lower end of the pipe.

11. A plug adapted to be moved downwardly through a well pipe that is open at its lower end, said plug comprising a radially expansible packer, means' controlling the expansibility of said packer, radially movable means adapted to engage the inside of said pipe to hold the plug against upward movement therein, a member movable longitudinally within said plug to actuate said packer control means and to expand said pipe engaging means, a spring for so moving said member, means for releasably holding said member against movement by the spring, the last mentioned means comprising a latch operating by movement out of the lower end of said pipe to release said member for movement by said spring, 7

gripping the inside cylindric surface of the pipe to hold the plug against downward movement I therein, a packer adapted to be expanded radially into fluid tight engagement with said pipe, a member having a bore receiving one end of the packer and normally maintaining said packer in radially constricted condition, spring operated means for releasing the packer from said boreand radially expanding said gripping means into engagement withvthe pipe at points above its lower end, and a latch normally engaging the inside of the pipe andreleasably holding said spring actuated means to maintain said packer and gripping means in radially contracted positions, said latch being operable by movement out of the lower end of the pipe to release said spring operated means and'thereby to cause the packer and gripping means to expand within the pipe.

13. A plug adapted to be moved downwardly through a well pipe that is open at its lower end, said plug comprising a tubular body, radially expansible wedge slips, a radially expansible packer, a packer control member extending longitudinally within said body and normally mainfiaining both the packer and wedge slips in radially constricted positions, means tending to move said control member to expand the packer and slips and means releasably holding said member against such movement, the last mentioned means being operable by movement out of the lower end of said pipe to release said memupward movement in the pipe, and latch means normally engaging the inside of the well pipe and releasably holding said control member against its packer and slip expanding movement, said latch means being operable by movement out of the lower end of said pipe to release said member to cause the first mentioned slips and packer to expand within the pipe.

GRANVELE S. KNOX.

86 wedge slips adapted to hold said plug against 

